How to get constraint “bottomSpace” from UIView Programmatically?

问题

I need change center of some views programmatically. 10 or more. I don't want to adding each bottom constraint as outlet, so could I search them from code like as:

for(NSLayoutConstraint *constraint in view.constraints)

Which attributes should I check? I need constraint for bottom space of superview.

回答1:

Have you heard about IBOutletCollection? When you link any object from IB to VC code, in popup window you can select IBOutletCollection Option. After link all constraints you want, only iterate this collection :)

@property (strong, nonatomic) IBOutletCollection(NSLayoutConstraint) NSArray *contentViewConstraints;


for (int i = 0; i < contentViewConstraints.count; i++) {
    NSLayoutConstraint *constraint = contentViewConstraints[i];
    //Center here
}

来源：https://stackoverflow.com/questions/29348661/how-to-get-constraint-bottomspace-from-uiview-programmatically